For some applications, such as digital, analog, RF or mixed signal circuits, passive components such as capacitors may be integrated with active devices on a single semiconductor die. Integration of such passive components leads to reduced fabrication costs, smaller physical size and increased reliability. In the case of capacitors, applications may include bypass capacitors to minimize power supply noise or other disturbances on a power supply, circuit capacitors for example in filter applications and charge storage capacitors for memory chips or imaging chips.
To date semiconductor manufacturers have had difficulty integrating capacitors on a semiconductor die, particularly with large capacitance values and/or for operation at high frequency. Large capacitance values require large areas, which consume space on the semiconductor die leading to greatly increased cost. To reduce die area consumed by large value capacitors, semiconductor manufacturers have developed trench capacitors in which the vertical dimension is utilized to increase capacitor area while minimizing surface area on the die.
Current trench capacitors utilize trenches etched into the conductive semiconductor substrate in which capacitors are formed. The conductive substrate results in parasitic coupling between the capacitor and the conductive substrate or other conductive elements, leading to a reduction in the frequency of operation of the circuit.
Further, capacitors and other passive components may be physically and electrically isolated from each other and from other conductive components including conductive components of active devices. When such conductive components come within close proximity to each other or other conductive components, interaction may occur between them resulting in reduced frequency of operation and/or compromised circuit performance, for example by cross-talk, where a signal from one conductive component is coupled into the signal from another conductive component.
For simplicity of illustration and ease of understanding, elements in the various figures are not necessarily drawn to scale, unless explicitly so stated. Further, if considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements. In some instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present disclosure. The following detailed description is merely exemplary in nature and is not intended to limit the disclosure of this document and uses of the disclosed embodiments. Furthermore, there is no intention that the appended claims be limited by the title, technical field, background, or abstract.